Palestinian medics prepare the lifeless body of Ibrahim al-Dawawsa, 12, who was killed in an Israeli air strike, in the morgue of the Shifa hospital, before his funeral in Gaza City, Friday, Aug. 8, 2014. Israel and Gaza militants resumed cross-border attacks on Friday after a three-day truce expired and Egyptian-brokered talks on a new border deal for blockaded Gaza hit a deadlock. (AP Photo/Hatem Moussa)

Palestinian medics prepare the lifeless body of Ibrahim al-Dawawsa, 12, who was killed in an Israeli air strike, in the morgue of the Shifa hospital, before his funeral in Gaza City, Friday, Aug. 8, 2014. Israel and Gaza militants resumed cross-border attacks on Friday after a three-day truce expired and Egyptian-brokered talks on a new border deal for blockaded Gaza hit a deadlock. (AP Photo/Hatem Moussa)

Palestinians carry the lifeless body of Ibrahim Al-Dawawsa, 12, who was killed in an Israeli airstrike, during his funeral in Gaza City, Friday, Aug. 8, 2014. (AP Photo/Hatem Moussa)

Smoke rises over Gaza City after an Israeli strike on Friday, Aug. 8, 2014, as Israel and Gaza militants resumed cross-border attacks on Friday after a three-day truce expired and Egyptian-brokered talks on a new border deal for blockaded Gaza hit a deadlock. (AP Photo/Hatem Moussa)

An Israeli man examines the damage to the roof of his house after a rocket fired from Gaza hit in a residential neighborhood of the southern city of Sderot, Israel, Friday, August 8, 2014. (AP Photo/Tsafrir Abayov)

Israeli people flee from an area after a rocket fired from Gaza hit in a residential neighborhood of the southern city of Sderot, Israel, Friday, August 8, 2014. (AP Photo/Tsafrir Abayov)

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GAZA CITY, Gaza Strip (AP) â€” Israeli airstrikes struck more than 20 targets Saturday in the Gaza Strip as militant rocket fire continued toward Israel following the collapse of a three-day truce aimed at ending the war between Israel and Hamas.

The Islamic militants resumed their rocket attacks Friday shortly before the 72-hour truce expired, drawing a wave of retaliatory airstrikes that killed at least five Palestinians. The fighting shattered a brief calm in the monthlong war and dealt a blow to Egyptian-led efforts to secure a long-term cease-fire between the bitter enemies.

More than 1,900 Gazans have been killed in the four-week war, roughly three-quarters of them civilians, according to Palestinian and United Nations officials. Israel disputes that breakdown, saying more militants have been killed. Sixty-seven people have been killed on the Israeli side, including three civilians.

The war grew out of the killing of three Israeli teens in the West Bank in June. Israel blamed the killings on Hamas and launched a massive arrest campaign, rounding up hundreds of its members in the West Bank, as Hamas and other militants unleashed rocket fire from Gaza.

On July 8, Israel launched an air campaign on the coastal territory, sending in ground troops nine days later to target rocket launchers and cross-border tunnels built by Hamas for attacks inside Israel.

Hamas, which violently seized control of Gaza in 2007, rejected several cease-fire offers throughout the fighting. Its primary demand is the lifting of an Israeli-Egyptian blockade imposed after they seized power. Militants had warned they would resume fighting after the cease-fire expired unless there was a deal to ease the restrictions.

The blockade, which Israel says is needed to prevent weapons from reaching Gaza, has led to widespread hardship. Movement in and out of Gaza is limited, and the economy has ground to a standstill and unemployment is over 50 percent.

Israel has said that the militants must disarm first, a demand dismissed by Hamas.

A delegation of Palestinian negotiators remained in Cairo in hopes of salvaging the talks. But participants said the negotiations were not going well. The Palestinian delegation met again late Friday with Egyptian mediators.

Azzam al-Ahmad, head of the Palestinian delegation, said the delegation would stay in Egypt until it reaches an agreement that “ensures” the rights of the Palestinian people. “We told Egyptians we are staying,” he told reporters.

The Israeli delegation to the Cairo talks left Egypt on Friday morning, and it was not clear if it would return. “There will not be negotiations under fire,” Israeli government spokesman Mark Regev said.

Egypt’s Foreign Ministry urged restraint by both sides and called for a new cease-fire to resume negotiations. The ministry said progress had been made in the talks but did not explain.

U.N. Secretary-General Ban Ki-moon expressed “deep disappointment” at the failure to extend the cease-fire and urged the parties to swiftly find a way back to the negotiating table, U.N. deputy spokesman Farhan Haq said.